Lubricating oil additives



Patented July 1, 1952 2,602,043 LUBRICATING omnnnrrivns Adlai E. Michaels, Cranford, and Niilo V. Hakala,

Rahway, N. 1., assignors to Standard Oil Devel'opment-Gompany, a corporation of'Delawai-e No Drawing. Application March. 8, 1951, Serial No. 214,652

compoundswhich, will be designated compatibility improvers.

Lubricating oil manu-iacturedby conventional methods are often unsuited for use under conditions: encountered in internal combustion engines andifor. diverseindustrial purposes vsatisfactory lubricating can, be generally given by almost, any i type of lubricant ofethe, proper viscosity for brief periods of time. However, fora-sustained service under normal operating conditions the quality of. lubricants becomes important andit is necessary for: the lubricant not onlyto carry out the. primary itmctions but also to. exhibit the following. advantages: '(1 the lubricant should operate satisfactorilyover; a wide temperature range and (2): the deleterious effects of. excessive engine deposits; shouldbeeountered. In order to achieve these performance objectives, important characteristics-of lubricating oils mustbe enhanced,

especially viscosity, viscosity index, and abilityto;

remove carbonaceous deposits; To obtain these and other desirable results, various additive materi'als have been blended with lubricating oils to extend the quality of lubricants for specific purposes beyond the level which can be reached by known manufacturing methods.

Generally, additives have been developed: for specific purposes, for example, pour point: depressants, viscosity index imp-rovers, sludge. dispersers, detergents, and the like. To obtain a. general purpose lubricant having a high level of performance with respect to pour point, viscosity index; sludge dispersion, and thelike,v it: isxnecessary' to incorporate in the lubricating oil base stock man-y varied additive materials: Because of the diverse nature or many of these materials, it is not' surprising that'- a certainincompatibilityamong them exists; For example, metallor-organ-ic compounds used as detergent additives-are frequently incompatible with high molecular weight polymeric materials used primarily as thickeners and viscosity index improvers. bricating oils having incorporated therein both of the above-mentioned additive materials are frequently unacceptable because of turbidity n has now been discovered that th addition or certain oxygenated organic compounds of the glycol ether type improves the compatibility of metallo-organic additives and highly polymeric additives, particularly the alkvl dibasi'c acid, ester-vinyl ester copolymeric additives; and corrects thereby the unacceptable turbidity of a lo;- bricant usingthe two; additives. K

These oxygenated organic compounds may be represented by the formula RO(CHR;'-CHR"Q-)"R!" where R is H or an alkyl grouphaving 1 to 8 carbon atoms, R" and R are H or analkyl group having 1 to 3 carbon atoms; R:""" is an alkyl group having l to- 8 carbon atoms and n is an integerfrom' 1- -8.

The polyalky-leneglycol ethers, especially themonoand di-alky r ethers-oi? polyethylene glycol and of polypropylene glycol, are preferred, in particular the methyl, ethyl, propyl and butyl ethers thereof. It has been found that thepolv-- ethylene and polypropylene glycol mono-alkyl ethers orester-ethers obtainable under the trade names Carbitol and Dowanol are particularly useful in improving the compatibility-of co'pol y meric additives and metallo-organic additives;

oxygenated organic-compounds of} the-class enumerated may be dissolved in oil mixtures or solutions which contain. incompatible additive fore: the addition of the polymeric additive or the metalIo-organio additive (2 to. the oili blend after the addition of either the polymeric additive. or the. metallororganic: additive, (3,) to the oil blend after the addition of the polymeric; act-- ditive-andi the metallosorganic additive (4-) to the metallo-organi'cadditives e To summarize briefly, the oil compositions'of this invention consist essentially of a mineral lubricating oil containing combined therein ('1) a copolyme'ric: material which imparts desirable properties ofviscositv' index improving: and/or pour depression, to the. blend, (271 a meta1loorganicadditive which is useful for improving the. detergency characteristic of the oil blend, and (3 acompatibility improver' which serves to minimize or eliminate any turbidity causedby' a mixture ofthe metallo-org-an-ic additive and the" copolymeric material; 9 V

The copolymerie materials useful, as

basic acid ester-vinyl ester copolymers. These copolymers may be formed by copolymerizing a di-alkyl maleate or fumarate ester with vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl laurate, and the like. The di-alkyl dibasic acid ester may be prepared by simply heating the desired dibasic acid or anhydride with approximately a double 1 molar proportion of the desired alcohol in the presence of an esterification agent such as sulfuric acid, hydrochloric acid, toluene sulfonic acid, and the like. It is preferred that the alcohol used as the esterification agent have an average of from 10 to 16 carbon atoms. An entraining agent such as an inert gas, naphtha and so forth is helpful for the removal of the water of esterification.

The copolymerization reaction taking place between the dibasic acid ester and the vinyl ester is ordinarily enhanced by the use of a polyoxide type catalyst among which may be mentioned benzoylperoxide, cumene hydroperoxide, tertiary butyl hydroperoxide, and the like.

In the preferred embodiment of this invention there is contemplated the use of a dialkyl dibasic acid ester-vinyl acetate copolymer in which the alkyl groups average from between 10 to 16 carbon atoms. An oil composition containing from 0.05% to 10% of the dibasic acid ester-vinyl acetate copolymer, preferably from 0.1% to 2.0%, percentages being by weight based on the weight of the total composition, is contemplated.

The metallo-organic additive material having the desirable detergency improving characteristics are preferably the metal salts of alkylated phenol sulfides or the reaction products of these sulfides and phosphorus sulfide. With these materials may be combined a minor amount of a petroleum sulfonate such as calcium petroleum sulfonate, calcium mahogany soaps, and the like. The barium salt of an alkyl phenol sulfide is particularly useful either alone or reacted with phosphorus sulfide. These materials are well known in the art of their preparation and are described in detail in United States Patent No. 2,362,291. It has been found that oil compositions containing from 0.2% to 0.3% by weight, based on the weight of the total composition, impart desirable detergent properties. A preferred range is from 0.8% to 2% by weight.

The compatibility agent, as described above, preferably diethylene glycol monoethyl ether is efficacious in amounts varying between 0.001 to 1.0% by weight, preferably 0.006% to 0.3% by weight.

In order to more explicity define the invention outlined above the following examples are given, it being understood that these examples are only illustrative of the inventive concept and not considered to be limiting in any way.

PREPARATION or DI-ALKYL MALEATE Esrsr A 3-liter flask equipped with a water trap and a reflux condenser was washed with 294 g. of maleic anhydride, 1118 g. of the alcohol obtained by hydrogenation of coconut oil and containing an average of 13.5 carbon atoms per molecule, 2 g. of sulfo-salicylic acid, 400 c. c. of xylene, and 200 c. c. of naphtha. The above mixture was refluxed for a total of 14 hours during which time 58 c. c. of water were collected. The reaction product was diluted with about 1,000 c. c. of benzol and then given four washes with 5% to sodium carbonate solution and two with water. The sulfides were removed by evaporafinal blend) tion on a steam bath. The resulting maleate ester had a saponification number of 230, a neutralization number of 0.5, and a viscosity of 210 F. of 41.7 S. U. S. and an average molecular weight of about 495.

GOPOLYMERIZATION or VINYL ACETATE WITH MALEATE ESTER A l-liter 3-necked flask equipped with a corn denser, stirrer, and a thermometer was charged with 200 g. of a lubricating oil having a viscosity at 210 F. 0144. S. U. S. and 300 g. of the maleate ester as prepared above. This mixture was heated to about C. after which it was blown with nitrogen for about 5 minutes. There was then added 4 g. of benzoyl peroxide and the mixture was again blown with nitrogen for about 5 minutes. Vinyl acetate addition was saturated with stirring about 45 minutes after the addition of the benzoyl peroxide and a total of g. of vinyl acetate was added during the course of 1% hours. The reaction mixture was maintained at 80 C. with stirring for 20 hours from the first addition of the vinyl acetate. The resulting copolymer had a viscosity at 210 F. of 3042 S. U. S. v

Example I A solvent extracted Mid-Continent parafiinic oil having a Saybolt viscosity of 46 seconds at 210 F. and a viscosity index of had added thereto 0.2% of an alkyl maleate-vinyl acetate copolymer prepared according to the technique outlined above. Ten separate samples of the above lubricating oil composition were set aside. To five of these samples were added 0.8% of five separate samples of inhibitor-detergents consisting of the barium salt of alkyl phenol sulfide reacted with phosphorus sulfide. All five blends were hazy or turbid initially and on several days standing, all blends were very turbid with a precipitate settling out in one blend. To the remaining five samples were added the same inhibitor-detergent additives but in this case the inhibitor-detergent additives contained diethylene .glycol mono-ethyl ether (suificient quantitles to give a concentration of 0.02% in the After standing two and a half months, the latter samples were found to be perfectly clear.

Example II Two samples were prepared as in Example I with the exception that a different alkyl dibasic acid ester-vinyl acetate copolymer was employed. The blend without the compatibility improver turned cloudy immediately, but the blend containing the diethylene glycol mono-ethyl ether (0.02% in final blend) was still clear at the end of the two and a half months examination period.

' Example III Example IV Example III was repeated except that a different sample of alkyl dibasic acid ester-vinyl estercopolymer was employed: and 0$02f%-*'instead of 0:047 compatibility improver wasemployed. Results were identical with those observed in Example III. Example V latter additives contained diethylene. glycol mono-ethyl ether sufiicient to give a final blend concentration of 0;02-5 All of the latter blends were clear after two and a half months standing.

Example VI Two. oil; blends were prepared using the. same test oil and same polyester copolymer (0.2%)v described in Example I. To one blend was added G'OMFATIBIIJITY OF POLYESTER OOPQLYMERS \VIPH'. METALLOeQRGeANIb ADrDLTlVES; is

[Blends contain 0.2% copoly-mer in extracted Midfiontinent oil heftvirga Saybolt viscosityief lfiseconds at; 2103-: F2. amba: viscosity prepared: To. (me blend- Was added0i&%. of Pzss treated barium iSoOetyl -phenol' sulfide; to'the second blend was added 0.04% methoxy trigly'col and 0 .8% oi? the same detergent additiveand to the third blend: was added j0'.'8% oi the same detergent additive which contained methoxy-triglyecl (0.02% concentration in final blend). The firstiblendf was cloudy'immediately while the two blends-containing thecompatibilityimprover were clear at; the end of two and a half' months.

. 1.1mm IX.

Two. blends. were. prepared using, the. same base stock, same polyester copolymer and. same detergentadditive. des,cr,ibed-in- Example VIII. To one oi the. blends was. added.'0.04% dimethoxytetraethyleneglycol- The blendwithout.thecom-' patibility improver cloudy initially whereas the, latter blend was. clear initiall-ybu't showed. a slight. haze, at. the end. of. a idday. low temper-- atnre} (140? F.) storage. test... I. 1

The; results. of the above. experiments may be summarizedas. follower 1 index 7 11 Appearanceoililend Appearance of Blend @tlith: I I Detergent Additive Compatibility-Improve! Containmg'Compatp out QQHIPatlDlIItYImQIQ-VZEI) E v .buitwlmpmver 0.8% Metal salt 0t allryl phenol sulfide+ -'I-urbidi'nitially; precipitates 0.02%. Diethylene; glycolrfiGElear end of 2%;

phosphorus sulfide. on standing. mono-ethyl ether. months. 0.08% Metal salt of alkyl phenol sulfide+ Haze initially; very turbid 0.02% Diethylene glycol phosphorus sulfide (4 samples). in several days. mono-ethyl ether. All clear end of 2% 1.0% Metal salt of alkyl phenol sulfide Slight haze in one week. 0.006% lglleiibygane glycol months.

mono-e y e er. 0.8% Metal salt of alkyl phenol sulfide Slight haze in several days; 0.006% Diethylene glycol Clear end of 2% cloudy-2 wks. mono-ethyl ether. months. 20% Metal salt of alkyl phenol sulfide+ Slight haze initially 0.025% Dlethylene glycol All clear end of 2 5 phosphorus 1sul)fide+calciu.m mahogany mono-ethyl other. months. soap 4 samp es 0.8% Metal salt of alkyl phenol sulfide+ Turbid initially; very tur- 0.04% Methoxy triglycol Clear end of 2% phosphorus sulfide. bid on standing. mon s. 0.8% Metal salt of alkyl phenol sulfide-I- do 0.02% Methoxy trlglycol Clear end of 2% phosphorus sulfide. months. 0.8% Metal salt of alkyl phenol sulfide+ d0 0.04% Dimethoxytetraethy- Clear Initially.

phosphorus sulfide. lone glycol 0.8% Metal salt of alkyl phenol sulfide+ Cloudy Initially 0.02% Diethylene glycol Clear end of 2% phosphorus sulfide. mono-ethyl ether. mon 0.8% Metal salt of alkyl phenol sulfide+ d0 0.04% Dlethylene glycol Clear end of 2% phosphorus sulfide. mono-ethyl other. months. 0.8% Metal salt of alkyl phenol sulfide+ .d0 0.02% Diethylene glycol Clear end of 2% phosphorus sulfide. mono-ethyl ether. months.

1 Compatibility improver added directly to oil blend.

1 Slight haze at end of 40-day low temperature (40 F.) storage test.

1.0% of a detergentinhibitor comprising the metal salt of alkylated phenol sulfide and to the second blend was added 1.0% of the same additive containing diethylene glycol mono-ethyl ether (0.006% concentration in final blend). The first blend exhibited a slight haze in one week whereas the blend containing the compatability improver was clear at the end of two and a half months.

Example VII Two oil blends were prepared using the same test oil and same polyester copolyrner (0.2%) described in Example I. To one blend was added 0.8% of calcium isooctyl phenol sulfide and to the second blend was added 0.8% of the same additive containing diethylene glycol monoethyl ether (0.006% concentration in final blend). The first blend exhibited a haze in several days and was cloudy in 2 weeks whereas the blend containing the compatibility improver was clear at the end of two and a half months.

Example V III Three oil blends composed of 0.2% alkyl dibasic acid ester-vinyl acetate copolymer and the same base stock described in Example I were acid ester containing from 10 to 16 carbon atoms in the ester portion thereof with a vinyl ester, from 0.2 to 3.0% of a metallic salt of an alkylated phenol sulfide or the phosphorus sulfide re action product of such metallic salt of an alkylated phenol sulfide and from .001% to 1.0% of a compatibility improver selected from the class consisting of diethylene glycol monoethyl ether, methoxy triglycol, and dimethoxy tetraethylene glycol. The preferred embodiment contemplates the use of a copolymer-of a maleic acid ester containing from 10 to 16 carbon atoms in the ester portion thereof, the barium salt of an alkylated phenol sulfide, and diethylene glycol ether.

This application is a continuation-in-part of Serial No. 67,085, now abandoned.

What is claimed is:

1. A non-turbid lubricating oil blend having a high viscosity and exhibiting a high degree of detergency which consists essentially of a minera1 oil base stock having combined therein about 0.05% to about 10% by weight of a copolymer of a maleate ester containing from 10 to 16 carbon atoms in the ester portion thereof and vinyl acetate, from about 0.2% to 3.0% by weight of a detergent inhibitor selected from the class consisting of metal salts of alkylated phenol sulfides and reaction products of metal salts of alkylated phenol sulfide, and a phosphorus sulfide, and from about 0.01% to 1.0% by weight of a compatibility improver of the class consisting of diethylene glycol monoethyl ether, methoxy triglycol, and dimethoxy tetraethylene glycol.

2. A non-turbid lubricating oil blend having a high viscosity index and exhibiting a high degree of detergency which consists essentially of a mineral oil base stock having combined therein about 0.1% to about 2.0% by weight of a copolymer of a maleate ester containing from 10 to 16 carbon atoms in the ester portion thereof and vinyl acetate, from about 08% to 2.0% by weight of a detergent inhibitor selected from the class consisting of metal salts of alkylated phenol sulfides and reaction products of metal salts of alkylated phenol sulfide, and a phosphorus sulfide, and from about 0.06% to 0.30% by weight of a compatibility improver of the class consisting of diethylene glycol monoethyl ether, methoxy triglycol, and dimethoxy tetraethylene glycol.

3. A lubricating oil blend according to claim 2 wherein the detergent inhibitor is the barium salt of an alkylated phenol sulfide.

4. A lubricating oil blend according to claim 2 wherein the compatibility improver is diethylene glycol monoethyl ether. V

5. A lubricating oil blend according to claim 2 wherein the compatibility improver is methoxy triglycol.

6. A lubricating oil blend according to claim 2 wherein the compatibility improver is dimethoxy tetraethylene glycol.

ADLAI E. MICHAELS. NIILO v. BLAKALA.

REFERENCES CITED The following references are of record in the file of this patent:

2 UNITED STATES PATENTS Number Name Date 2,091,627 Bruson Aug. 31, 1937 2,122,593 Stafford July 5, 1938 2,123,641 Wiezevlch July 12, 1938 2,281,623 Schott May 5, 1942 2,338,522 Liberthson Jan. 4, 1944 2,370,080 Schreiber Feb. 20, 1945 

1. A NON- TURBID LUBRICATING OIL BLEND HAVING A HIGH VISCOSITY AND EXHIBITING A HIGH DEGREE OF DETERGENCY WHICH CONSISTS ESSENTIALLY OF A MINERAL OIL BASE STOCK HAVING COMBINED THEREIN ABOUT 0.05% TO ABOUT 10% BY WEIGHT OF A COPOLYMER OF A MALEATE ESTER CONTAINING FROM 10 TO 16 CARBON ATOMS IN THE ESTER PORTION THEREOF AND VINYL ACETATE, FROM ABOUT 0.2% TO 3.0% BY WEIGHT OF A DETERGENT INHIBITOR SELECTED FROM THE CLASS CONSISTING OF METAL SALTS OF ALKYLATED PHENOL SULFIDES AND REACTION PRODUCTS OF METAL SALTS OF ALKYLATED PHENOL SULFIDE, AND A PHOSPHORUS SULFIDE, AND FROM ABOUT 0.01% TO 1.0% BY WEIGHT OF A COMPATIBILITY IMPROVER OF THE CLASS CONSISTING OF DIETHYLENE GLYCOL MONOETHYL ETHER, METHOXY TRIGLYCOL, AND DIMETHOXY TETRAETHYLENE GLYCOL. 